From the November RealBeer newsletter:
____Reply Separator_____ Perhaps the alcohol has nothing to do with it.
Color Blindness: More Prevalent Among Males
Some 10 million American men—fully 7 percent of the male population—suffer from color blindness, but it affects only .4 percent of women. The fact that color blindness is so much more prevalent among men implies that, like hemophilia, it is carried on the X chromosome, of which men have only one copy. (As in hemophilia, women are protected because they have two X chromosomes; a normal gene on one chromosome can often make up for a defective gene on the other.)